Mmm, it all depends how old your 40GB harddisk is. When i is quite new then the speed difference might not be that great to your 60GB harddisk. To reach maximum security, you can do this:
1.) Install your 60GB HD as your secondary drive (usually D
.
2.) Put all your "Your Files"-Folder on D:, especially your Email and Address-Data (bad memories
).
3.) Backup these files regularly to C:
4.) Once in a while (4 weeks or so) make a disk-image from C: to D:.
In the case that C: goes bye-bye, you can restore your system with all the data in less then 20 minutes to the point of the Last disk-image. This has saved my bud several times now.